Patent Literature 1 discloses a previously-proposed technique. In this technique, a shift-start delay of a shift control (speed ratio control) for a continuously variable transmission is set at a relatively large value with an identical accelerator opening, in an environment such as highlands in which engine torque is reduced.
In the case that oil pressure which is supplied to a movable sheave of each pulley of a belt-type continuously variable transmission is set based on a request torque, if an actual engine torque is reduced due to the highlands or the like, an excessively high oil pressure relative to an actually inputted torque is supplied to the movable sheave. In this case, when the speed ratio fluctuates due to a disturbance or the like, a vibration occurs in the vehicle regardless of the shift-start delay of the shift control. This new problem was found by the inventors of the present application. It is therefore an object of the present invention to provide an oil pressure control device for a belt-type continuously variable transmission, devised to avoid unnecessary vibration by virtue of a stable speed-ratio control.